Alphys Takes Action
by mattjdupree
Summary: Genocide spoilers. Chara's playing through the timeline again, killing everyone in their path for the umpteenth time. When Chara strikes down Undyne, Sans slips up and mentions the other timelines. Alphys decides that she's had enough of Chara's DETERMINATION. Alphys/Undyne. Amalgamations.
Chapter 1 | Consequences

-ATA-

 **A/N:**

 **Credit where credit is due; this was inspired by** _ **Undertale - Alphys Takes Action (Original Remix)**_ **by Luke Neujahr on YouTube and by** _ **Alphys's Amalgmates**_ **by Omoni on FanFiction dot net. I was listening to the song and thinking, "If Alphys had enough DETERMINATION stocked, she could take on Chara/Frisk!"**

 **And some other headcannons seeped in, causing this...**

-ATA-

Alphys hadn't given much thought to _after_. She'd been so filled with determination - even before injecting herself with the DETERMINATION…

If there was one thing she wished, though, melting on the floor of the judgement hall, it was that she hadn't revived Undyne. The fish-lady was now well on her way to an amalgamate state, somewhere in the puddle. With one SOUL between them, and the enemy defeated, their collapse hadn't taken long.

-ATA-

" _Undyne!" Alphys shouted at the screen. "N- no. Please."_

 _The human began walking away, even before Undyne finished melting._

" _By now she's called Asgore and told him to absorb the six human SOULs," Undyne said to the retreating human's back. "And with that power…"_

 _Alphys clambered over the controls and put her claws on the screen. "Nonononono U- Undyne! Use the D- DETERMINATION again! P- Please! PLEASE!"_

" _This world," Undyne was practically gurgling her speech now - her last breath, "will live on…!"_

 _Alphys stored, frozen, at the small pile of white on the screen._

 _And then, in the silence, she heard a whisper followed by a curse._

 _She spun, tripping over the controls as she came off of the screen. "What did you just say Sans?"_

 _Sans was standing behind her, next to Mettaton. He was holding a dusty red scarf she didn't want to think too much about. For once, his face had dropped his ridiculous smile. "what? nothing."_

" _Alphys, Darling…" Mettaton looked like he was trying to handle the situation delicately. "I've started the evacuation tapes we prepared earlier, but… Shouldn't you call Asgore?"_

 _Alphys ignored him. "D- Don't tell me that was nothing! Y- you said 'it never gets easier.' W- what doesn't?"_

 _Sans clutched the scarf tighter. "it's nothing. i have to go." He began walking toward the elevator._

" _Sans! P- please! If you know something…" Something what? What could Sans possibly know about the human that could be useful? Stupid, stupid-_

 _Sans paused. "it… it never gets easier to watch this. papyrus, undyne, mettaton… every monster that gets in that_ thing's _way."_

" _What? But, Darling, I'm still here!" Metatton said, confused._

 _Sans looked back at Mettaton nervously. "nevermind. i said too much."_

 _Before Sans could resume walking, Alphys blocked his path to the elevator. "Y- you can't j- just drop a hint like that a- and l- leave! Why d- did you put Mettaton in your… your dead-people list?"_

 _The pained look on Sans' face turned to one of anger. "it's nothing, alright? just a stupid mistake. let me go." He tried to walk around her._

 _She blocked his path again. "Sans P- PLEASE! I- I'm b- begging y- you!"_

 _Sans squeezed the scarf, bunching it up into a ball. "fine. y'know what? fine. this kid- the human, they've done this before. over and over and-"_

" _D- done this before?"_

" _killed. all of us. i remember bits and pieces of the other timelines. there was one, maybe two where we got to the surface. the kid befriended everyone, led us all out. then, that first night, poof. all back to zero. that kid has enough DETERMINATION to undo everything up to when they gained control of the timeline, sometime this morning."_

 _Alphys gaped. Mettaton stopped sliding back and forth on his wheel to maintain his balance, instead leaning up against the screen's console._

" _and then they started killing people. at first just a few froggits. then everything in the ruins. then toriel. then... paps too. then... everyone. every single person, over and over, searching every corner to hunt us all down. every time they'd take down mettaton with a flick of the wrist. just one hit."_

 _Alphys' mouth worked behind her claws, held up in shock. That… that demon!_

" _i tried to change things. every change i made caused that human to just move faster. they looked_ interested _again. i tried to save pap, they killed me early. i tried to hide myself, they broke through the hotlands force fields by tinkering with the core, and killed all of you. i tried just being one of the crowd, ignoring it and acting like i did the first time. but it hurts. so much."_

 _Alphys felt the need to sit down, unable to handle this new information. She promptly did so, on the floor._

" _so… there. what i know. you wanted it, you got it. i'm… i'm going to go wait for that_ thing _to make it to asgore. i'm bone tired." He walked around Alphys, toward the elevator. Then he walked past it, disappearing into what appeared to be solid wall._

" _Alphys… maybe if we-"_

" _D- DETERMINATION. Of c- course it had to be DETERMINATION."_

" _Alphys!" Mettaton wheeled over, grabbing her shoulders. "We need to finish my body. My body-body. The human eradication form, to stop that-"_

" _B- but, th- that's exactly what we did, isn't it? A- and j- just one hit…"_

" _Alphys…"_

" _N- no. I- I won't let this happen again. We're going to stop the human." DETERMINATION was the key. Most monsters couldn't handle it._

 _But one monster just had..._

" _By finishing my body?"_

" _No. N- No use repeating the past. Mettaton… p-please… s- stall for time like this. I h- have a plan."_

" _You want me to stall for time as a quiz bot?!"_

 _Alphys gave the monitor screen on the wall an evil glare, staring just next to the patch of white, where the human had struck Undyne down. "Give them hell. I intend to finish the job."_

-ATA-

Alphys berated herself for her past failures as she lost track of her arm somewhere in the goop. Or, maybe it was just submerged. She couldn't move it, but she didn't really feel like caring.

-ATA-

 _Alphys waddled down the path as quickly as she could while carrying the pack full of vials and syringes. She had taken a tunnel past all the steam vents and puzzles of Hotlands; she couldn't afford to break any of the equipment, and she wasn't really one for leaping over lava anyway. That had been - no, was and would be - Undyne's thing._

 _She found the patch of dust in the middle of a path, just next to a bridge. It sat only slightly disturbed by the wind. Alphys fell to her knees next to it._

" _Undyne. I- It's going to be okay, okay? Y- you can handle DETERMINATION. Y- you're stronger than-" Alphys choked on her words, remembering her mistakes in the True Lab. "You'll… You'll be yourself, right?"_

 _The dust said nothing. Alphys un-shouldered the bag of gear and pulled out one of many, many vials of DETERMINATION._

" _I- I- Y… Y- you'd forgive me for this, r- right? I- it's for everyone's g- good. W- we have to stop that human, and the only way to do that is to have m- more D- DETERMINATION. And- and- and- you already have a little, I mean, from the… the… the... ice cream."_

 _The dust said nothing._

" _I- I'm not making another m- mistake," Alphys told the dust. "Th- this is the right thing to d- do."_

 _She uncapped the DETERMINATION and poured…_

 _. . ._

 _It seeped through the dust, into the ground. Nothing happened._

-ATA-

"You IDIOT."

Alphys raised her head - whatever was left of it - from the goop of DETERMINATION that had previously been her body. And Undyne's.

-ATA-

" _UNDYNE! PLEASE!" Alphys shrieked at the tiny puddle of DETERMINATION. She'd lost count of how many vials she'd poured onto the dust - enough that the ground had saturated and a small puddle had formed on the surface._

 _The puddle was of pure DETERMINATION, the dust drifting and settling uselessly on the surface._

" _I- I th- thought th- this w- would w- work."_

 _The dust swirled on the pool's surface. For a moment Alphys hoped something was happening, then she moaned as she realized it was only vorticity effects caused in the liquid by having her warm body near one side and cold air on the other._

 _Alphys shut her eyes, feeling tears leaking out. "P- please…"_

 _Her eyes fell to the bag._

 _. . ._

 _Why had she brought syringes to give DETERMINATION to dust?_

 _Memories of the amalgamates struck her. Monsters melting, fusing, becoming abominable, powerful creatures. And all because… because of the…_

 _Hands shaking, she drew another a syringe. Maybe if she took just a little of it from the puddle, she could… help Undyne rebuild her form. There_ had _to be a way._

-ATA-

"You make all those messes out of DETERMINATION - you make ME - then you think it would be worth it to shoot yourself up with the stuff?" A golden flower bobbed just above the tiled floor, its stem cracking through a tile and leaving small chips strewn about.

-ATA-

 _The DETERMINATION burned like fire in her veins. Clearly the ice cream had been a wonderful way to cover the small doses… this was painful, almost distractingly so._

 _She dropped the now empty syringe, staring down at the puddle of DETERMINATION on the ground in Undyne's dust. Stupid! Stupid! She couldn't have just_ some _of the dust in the puddle, she needed_ most _of it - more of it! Hurriedly, before any more DETERMINATION escaped into the ground, Alphys scooped dust onto the puddle._

… _She tried to, anyway. The dust stuck to her claws, refusing to slide off into the puddle. She shook her head, scooting closer to the pile and taking another clawful on top of the first. This, too, stuck._

 _She shook her hands, trying to get the dust off and into the puddle of DETERMINATION. If she could just get enough of Undyne into the-_

 _Her knees suddenly gave, like they'd turned to jelly, and Alphys collapsed face-first into the Undyne dust/DETERMINATION puddle._

-ATA-

Alphys sank further into puddledom. It figured that one of her mistakes would be back to mock her. It only served her right. Then again, it wouldn't have long to mock her at all; soon she'd just be instinct and DETERMINATION, some kind of fish-lizard non-sentient monster. She… she and Undyne. Together, at least.

Not that the captain of the royal guard would want that, but… it had been the right thing to do.

-ATA-

 _Undyne looked down at herself. She… she had melted, hadn't she? Even with all the determination she felt, her refusal to die, everyone's hearts beating as one, that hadn't been enough._

 _So why was she still here? And why did she feel so sorry? And_ where _in blazes was that human-shaped_ thing _?_

 _She was wearing a lab coat. Well, wearing was a generous term - it had shredded to accommodate her shoulders, so it was more like wearing white armbands, a button-down tank-top, and underwear._

 _...not her underwear._

" _W- what?" Had she just stammered? She didn't stammer! She was Undyne the Undying! She didn't even die when her death got deader! She felt around her face. Hair, gills, glasses, two eyes…_

" _G- glasses?! T- two eyes?!"_

 _Something had happened. Something big had happened, and it definitely involved some serious nerd crap. The question was, what…_

 _Memories. Memories that weren't hers were in her head, of watching herself fighting the human through a screen, of watching Sans break down, of pouring a glowing liquid on a pile of dust…_

" _A- Alphys? Where are you, y' nerd? You did it! I'm b- back!" The stuttering was getting annoying. She knew what she wanted to say, it was like her confidence was faltering whenever she tried._

" _A- Alphys?"_

 _Undyne felt a throbbing and looked down again. Her SOUL had just pushed its way out of her chest, and was hovering before her._

" _Alphys?" Undyne asked the SOUL, a sinking realization dawning on her._

Pouring a glowing liquid on a pile of dust…

 _That wasn't her SOUL. That was Alphys; Alphys'. Maybe she, Undyne, was Alphys, too, but with her own - Undyne's memories. If she was in the lab coat, and the glasses…_

" _I- I'm s-s-so s-sorry," she choked, though the words weren't hers, or in her voice, instead just coming from her mouth._

 _Then, as suddenly as it had popped out, the SOUL began flitting off down the path._

" _HEY! Get back here nerd and tell me what just happened!"_

-ATA-

"How does it feel now? Knowing how it felt for all those monster amalgamates to melt? To lose THEMSELVES? To lose their MINDS? Their EMOTIONS? Their love and compassion? To have it all replaced with LOVE?"

Alphys tried to think of something to say. She couldn't bring herself to… anything.

"Well? 'Doctor' Alphys? How's that healing going now?"

-ATA-

 _Undyne doubled over gasping as she finally caught up with her SOUL. Or, possibly, the one she was sharing with Alphys. She wasn't really sure how identity worked in this situation, not that it mattered._

 _Gentle snoring came from the next room. Undyne took a moment to glance around; it seemed she'd run halfway across the Underground. They were just before the judgement hall in Asgore's castle._

" _G- good. S- Sans is still-" Undyne began to mumble to herself, in Alphys' voice and seemingly without her control._

" _what? didja think i would just stand there and take i-"_

 _Sans' last word cut off with a cough as Undyne rounded the corner. The human stood over the skeleton, knife dripping with glowing red as Sans bled onto the tiled floor._

" _undyne? with two eyes? and no pants? that's new, though i suppose hallucinations are like that after a while…" He coughed, glowing red splattering his jaw and the human's shoes. "nice legs, fishy girl."_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human turned around, staring at her… and smiling._

 _The sight of the smiling, evil, dust-covered human filled her with DETERMINATION._

-ATA-

Alphys felt her neck beginning to dissolve into the DETERMINATION slurry. That was fine. She'd be gone entirely soon.

"Alphys?"

The voice reminded her of Asgore, on one of his concerned calls asking about the amalgamates - stern and mildly worried at the same time. Strange that the flower would sound so much like him, considering that flowerbed was where King Asgore's only son had died…

Oh. One more mistake for the tally. It only figured she'd mess up badly enough to resurrect a soulless version of her boss's son. That was just like her.

-ATA-

" _Y- YOU!" Undyne stalked forward, fury in her gaze._

 _The human cocked its head, smile widening._

" _NGAAAAH! I D- Don't even care about getting your SOUL to Asgore anymore! Someone like you doesn't d- deserve even a moment after death! I will stomp your SOUL to pieces!"_

" _You're stuttering," the human said, "That's new. I was wondering why Mettaton died when I flipped his switch. Also, where is your armor? That lab coat hardly covers-"_

 _A spear materialized in Undyne's hand. "NGAAAAH!"_

-ATA-

"Alphys… Oh forget it. What does it matter anyway? Once you melt and forget how to use your DETERMINATION, I'll be the one in control of the timeline again. ALL. ME!"

-ATA-

" _N- No. No! N- not again! N- not now! J- just one hit, even with so much DETERMINATION..."_

 _The human put its knife in its pocket, then smiled sweetly at the melting Undyne._

" _I don't understand! WHAT WILL IT TAKE TO END YOU?!"_

 _The human frowned. "Do you think that smile will work on Asgore, or should I do something a little more scared?"_

 _Undyne fell forward, leaning on one melting arm. "Why do you…" She trailed off as she felt the liquid leaving her, the DETERMINATION evaporating and leaving her only dust._

 _LOAD_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human turned around, staring at her… and opening their mouth in shock._

 _They snarled. "I must have accidentally… fine. I'll just beat you again."_

" _NGAAAAH!" Undyne threw her arm before the spear even materialized._

-ATA-

"You don't remember, but I killed you slowly so many times. And you know what? You didn't even fight it. You thought you deserved pain after what you did."

-ATA-

 _LOAD_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human turned around, throwing the knife..._

 _LOAD_

 _LOAD_

 _LOAD_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human turned around, ducking the spear Undyne threw and charging forward..._

 _LOAD_

 _LOAD_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human turned around, just barely jumping in time to avoid losing a foot. They deflected several more spears with their knife blade, then ran forward…_

 _LOAD_

-ATA-

"But this? Don't you even care? You won't _exist_ anymore!"

-ATA-

 _LOAD_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human turned around, searching for where Undyne should have been. She wasn't there._

 _The human began to run toward the end of the hall - toward Asgore and a RESET - but tripped over a speartip poking out of the ground. It was all the human could do to roll left and right to dodge the spears dropped toward them, until they spotted a glimmer of red hair behind a column._

-ATA-

"Maybe I'll tear your new Undyne-amalgamate apart - take that one SOUL away from you both? How about that!"

Alphys realized that - even if she wanted to - she couldn't open her mouth. The only thing above the surface of the puddle was her eyes.

"Wait, but if I have control over time, I could go back to before you killed… Oh, if I ever made that mistake-!"

-ATA-

 _LOAD_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human turned around, only to writhe in pain as their feet were pierced by speartips. They fell to the ground, onto an already waiting spear._

" _So th- that's why S- Sans was s- so lazy," Undyne said, striding forward. The human clutched at the hole in their chest, trying to lift themselves off the spear. "S- simplest solution was best."_

 _In the human's writhing, Undyne didn't notice the flick of their wrist, or the flash of metal._

-ATA-

"Whoever has the most DETERMINATION controls the timeline. If I had all the DETERMINATION you used then Chara could never..."

Alphys thought about a warm sand dune. Some place to sun herself, that'd be nice. Maybe near water, so she could watch… Watch who? She forgot. It had seemed like someone important...

"N- no! You deserve this, Alphys! I can't just… Oh, but if I go back too far, even once! I don't want… They'll just… No they wouldn't! I'm their best friend! Maybe…"

Alphys didn't notice when she stopped being able to see. It didn't matter; everything she needed to see was in her head. Seaweed and sand and water and sunlight…

"I… I can't. I can't go through that again. I can't…"

-ATA-

 _LOAD_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human jumped immediately over Sans' dust, avoiding the few spears rising out of the ground to impale them._

" _NGAAAAH! STAY DEA-"_

 _The human spun, putting their whole body motion into hurling the knife._

-ATA-

"Remember Alphys, Undyne, I still hate you both. I'm doing this for myself, okay? The moment I find a way to undo this, I'm out, got it?"

-ATA-

 _LOAD_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human flinched away from where a spear came up directly in front of their face…_

 _...and right onto one rising behind them. It drove through the human's back, lifting them off the ground. Another two shot up, piercing the human's wrists. They dropped the knife._

" _H- hah! F- finally got you for good!"_

 _Undyne walked forward, already feeling so very tired._

" _We win." A spear slammed through the other side of the human's chest. "No more k- killing people for you, human."_

 _Undyne didn't see the human's foot snap out, but she felt the ballet shoe connect with her face._

 _LOAD_

 _Then Sans collapsed to the floor, turning to dust and leaving only his jacket. The human saw the spear rising in front of them and grabbed it, pulling themselves upward and forwards in a jump over Sans' body._

 _The spears cut cleanly through the hoodie, and the human._

" _No, I- I won't fall for that again. Sans is gone, and_ that's your fault!" _Undyne punctuated her words with more spears, filling the human with glowing magic. "I don't care if he's a friend, his dust won't stop me from getting you!"_

 _The human gurgled incomprehensibly. Undyne couldn't see their face, but she wished she could watch the pain and horror in that monster's eyes._

" _Toriel." Spear. "Froggits." Spear. "Loox." Spear. "Snowdrake." Spear. "Icecap." Spear. "Papyrus." Spear._

 _This went on for some time, until finally the human's SOUL shone through the holes in its body._

" _M- Mettaton…" Spear. "S- Sans." Spear._

 _Undyne felt herself slipping. She was so tired, she wanted to collapse into a puddle again. But she wasn't done. Her SOUL felt it. There was one last name on the list._

" _and ALPHYNE!" Four spears pierced the human's SOUL all at once. It burst like a balloon._

" _... Alphys…" Undyne said. She felt, smaller. Her confidence was slipping. Her memories hazy. She just wanted to… swim? That sounded right. At a beach, so she could be near warm sand for…_

 _For…_

 _For..._

-ATA-

Alphyne said nothing.

"Ew. I can't believe I'm doing this! Just… right in… the puddle..."

A flower bloomed in the middle of the puddle. It melted. The new personality easily won control over the DETERMINATION and SOUL from what remained of the others.

A massive form emerged at the end of the hall, a red trident gripped in one huge paw. "Hello? Is someone here? I apologize, I thought I heard some shouting, but I was busy watering the flowers in the-"

Alphyne Dreemurr RESET.

-ATA-

 **A/N:**

 **I'm using RESET mechanics that go back to when the given SOUL got enough DETERMINATION to control the timeline. Flowey is an exception to the rule because Flowey. He doesn't need a SOUL to control time because he's Flowey. Stop asking questions.**

 **Now, smart readers will note that Flowey decides to go Asrielphyne out of fear of Chara. "But, if that's the case, why did he intentionally do what he was afraid of?" He did it in a way that made sure he'd have more DETERMINATION than Chara: by inhabiting Alphyne, who already did have more DETERMINATION. Now Flowey never has to fear Chara again, because he's the one with the RESET. If he doesn't like what Chara's doing, he can just turn others against her, or take advantage of time mechanics to kill her. Imagine the Omega Flowey fight where the SOULs agree with Flowey. Not fun for Chara.**

 **And, best yet, Flowey got a SOUL from Alphyne. If he can manage to keep the other two personalities at bay, he can be Asriel again.**

 **That's a big if.**

-ATA-

 **A/N 2:**

 **I don't plan on continuing this one. I had a decent story written out, but I ended up backing the "good" characters into a temporal corner I couldn't pull them out of, so I decided to scrap it. Also, when Frisk finally showed up, I think I wrote them badly.**

 **And there wasn't nearly enough Alphys later on to deserve the title.**

 **Anyway, this is going to be a oneshot. Feel free to steal any ideas from this story, if you want to. I doubt I'm the only person who came up with Alphys actually becoming an amalgamate (though I didn't see any other stories where that happened.)**


End file.
